The IMP77 Intermediate code
                  Internal representation

   In production compilers the mnemonics used  in  the  text
are  output  in  an  abbreviated  form,  each mnemonic being
translated into a single ASCII printing character.

     !   OR            G   ALIAS         c   MCODE
     "   JUMPIFD       H   BEGIN         d   DIM
     #   BNE           I   unused        e   EVENT
     $   DEF           J   JUMP          f   FOR
     %   XOR           K   FALSE         g   unused
     &   AND           L   LABEL         h   ALTBEG
     '   PUSHS         M   MAP           i   INDEX
     (   unused        N   PUSHI         j   JAM
     )   unused        O   LINE          k   unused
     *   MUL           P   PLANT         l   LANG
     +   ADD           Q   DIVIDE        m   MONITOR
     -   SUB           R   RETURN        n   SELECT
     .   CONCAT        S   ASSVAL        o   ON
     /   QUOT          T   TRUE          p   ASSPAR
     :   LOCATE        U   NEGATE        q   ALTEND
     ;   END           V   RESULT        r   RESOLVE
     <   unused        W   SJUMP         s   STOP
     =   unused        X   IEXP          t   unused
     >   unused        Y   DEFAULT       u   ADDA
     ?   JUMPIF        Z   ASSREF        v   MOD
     @   PUSH          [   LSH           w   SUBA
     A   INIT          \   NOT           x   REXP
     B   REPEAT        ]   RSH           y   DIAG
     C   JUMPIFA       ^   PROC          z   CONTROL
     D   PUSHR         _   SLABEL        {   START
     E   CALL          a   ACCESS        |   ALT
     F   GOTO          b   BOUNDS        }   FINISH